Fertigation Efficacy Enhancement System And Associated Methods

ABSTRACT

A fertigation system includes a circulation pump positioned in-line in a closed-loop, low-flow tubing delivery means. The circulation pump acts to agitate and substantially equalize a concentration of nutrients in fluid within the tubing, thereby preventing a concentration gradient from being established by upstream plants receiving preferential exposure to the nutrients relative to downstream plants. The circulation pump should preferably be configured not to substantially raise a fluid pressure within the tubing.

CROSS-REFERENCE TO RELATED APPLICATION

The present invention claims priority to provisional patent application Ser. No. 61/329,867, filed Apr. 30, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems and methods for providing fertilizer to plants, and, more specifically, for providing fertilizer via low-flow irrigation systems.

2. Description of Related Art

It has been found during the use of low-flow systems, such as are typical with porous membranes, that most commercial fertilizers, even though water soluble, often fall out of solution, or “settle out.” When this happens, the amount of fertilizer available for plant use decreases in proceeding farther and farther from the fertilizer injection point.

In the case of systems using porous membranes, such as taught in commonly owned U.S. Pat. Nos. 7,198,431, 7,712,253, and 7,748,930, it may be that, as a plant pulls fertilizer from the porous membrane, the fertilizer concentration inside the membrane decreases, thereby decreasing the amount of fertilizer available to plants downstream.

Such a phenomenon is not an issue with high-flow, as the flowing fluid (water and fertilizer) carries the nutrients to the plant along with the water. However, with the systems such as the low-flow porous membrane system, this flow rate can be down to a level of extraction at the rates at which plants absorb water and fertilizer.

In testing the feeding system and method of the above-referenced '431 patent and '827 and '863 publications, a decrease in fertilizer concentration was noted. With tomato plants placed along a 100-ft membrane 1 in. in diameter, plant growth was seen to decrease at a distance of approximately 50 ft downstream of the fertilizer injection point, with continuing decrease further downstream. In recent tests, with the current pull rates of nutrition and water, it has been found that it takes approximately 30 days for water and/or nutrient to pass from the membrane feed inlet to the opposite end of the membrane. While this time is a function of environmental and biological factors, it serves as a demonstration of how substantially low the flow rates can be.

SUMMARY OF THE INVENTION

The present invention is directed to a system and method for increasing an efficacy of a fertigation system, wherein the fertigation system comprises a low-flow system including a tubing-based delivery apparatus.

The fertigation system of the present invention comprises a circulation pump positioned in-line in a closed-loop, low-flow tubing delivery array. The circulation pump acts to substantially equalize a concentration of a substance such as a nutrient in fluid within the tubing, thereby effectively preventing a concentration gradient from being established by upstream plants receiving preferential exposure to higher concentrations of the substance relative to downstream plants. The circulation pump should preferably be configured not to substantially raise a fluid pressure within the tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of a fertigation system.

FIG. 2 is a cross-sectional view of a second embodiment of a fertigation system.

FIG. 3 is a close-up view of a return feed portion of the embodiment of FIG. 2.

FIG. 4 is a cross-sectional view of a third embodiment of a fertigation system.

FIG. 5 is a cross-sectional view of a fourth embodiment of a fertigation system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description of the preferred embodiments of the present invention will now be presented with reference to FIGS. 1-5. Although a number of embodiments will be presented herein, it will be understood by one of skill in the art that departures from the exact constructions illustrated and discussed are intended to be subsumed within the present invention.

A first embodiment of a fertigation system 10 is illustrated in FIG. 1. A feed inlet 11 is positioned in fluid communication with a tubing inlet 12, leading to outbound tubing 13. The outbound tubing 13 is connected at a distal end 14 to a distal end 15 of return tubing 16 using, for example, a “U” fitting 17, although this is not intended as a limitation. Simple connectors can be sealed by welding, for example, using a hand-held welder, or by clamping. A slide assembly can also be used at the tubing ends, which would require no tools in the field for connecting and sealing.

A proximal end 18 of the return tubing 16 is connected to an inlet 19 of a pump 20, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention. The pump 20 should preferably have the attribute of adding no substantial additional pressure to circulating fluid within the tubing lumen 21.

An outlet 22 of the pump 20 can connected adjacent the tubing inlet 12, thereby providing circulation and substantial fertilizer concentration equalization within the tubing lumen 21.

A second embodiment of a fertigation system 30 is illustrated in FIGS. 2 and 3. A feed inlet 31 is positioned in fluid communication with a tubing inlet 32, leading to outbound tubing 33. The outbound tubing 33 is connected at a distal end 34 to a distal end 35 of return tubing 36 using, for example, a “U” fitting 37, although this is not intended as a limitation.

A proximal end 38 of the return tubing 36 is connected to an inlet 39 of a pump 40, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention. The pump 40 should preferably have the attribute of adding no substantial additional pressure to circulating fluid within the tubing lumen 41.

A difference between this embodiment 30 and that 10 discussed above comprises that an outlet 42 of the pump 40 is connected with the tubing inlet 32 at an acute angle 43 (FIG. 3), which decreases agitation in the low-flow-rate system. Again, this embodiment thereby provides circulation and substantial fertilizer concentration equalization within the tubing lumen 41.

In a third embodiment 50 (FIG. 4), the feed inlet 51 is positioned in fluid communication with a tubing inlet 52, leading to outbound tubing 53. The outbound tubing 53 is connected at a distal end 54 to a distal end 55 of return tubing 56 using, for example, a “U” fitting 57, although this is not intended as a limitation.

A proximal end 58 of the return tubing 56 is connected to an inlet 59 of a pump 60, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention.

A difference between this embodiment 50 and those 10,30 discussed above comprises that an outlet 62 of the pump 60 is in fluid communication with tubing 63 that leads back to a storage tank 64. Here the pump 60 can deliver a higher-pressure feed, as the effect of any agitation would be delivered to the storage tank 64 and not the irrigation tubing 53,56. Thus the pressure within lumina 65,66 of the tubing 53,56 is maintained at a substantially constant value determined at least in part by an elevation head of the storage tank 64.

In a fourth embodiment 70 (FIG. 5), the feed inlet 71 is positioned in fluid communication with a tubing inlet 72, leading to respective inlets 81 a,81 b, . . . of a network 73 of parallel outbound tubing sections 73 a,73 b, . . . . The outbound tubing network 73 is connected at respective distal ends 74 a,74 b, . . . to a manifold 75 leading to a proximal end 76 of return tubing 77.

A distal end 78 of the return tubing 76 is connected to an inlet 79 of a pump 80, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention.

As with embodiment 50 discussed above, an outlet 82 of the pump 80 is in fluid communication with tubing 83 that leads back to a storage tank 84.

As discussed above, the pumps 20,40,60,80 can comprise any type of pump usable in the target setting, although a peristaltic pump is believed to represent the best mode at the time of filing.

In use, the pump 20,40,60,80 can run continuously or can be triggered intermittently depending upon the pump displacement and the length of the run. To ensure the fertilizer is kept in solution, and the concentration is substantially consistent, at least one full fluid rotation is believed preferable to be completed every several hours, the cycle time preferably designed to maintain a substantially constant concentration and keep the fertilizer in solution. Since the pump is run under low pressure and at a flow rate large enough to just cycle the fluid, the pump could be powered by a small solar panel when placed remotely.

Additional embodiments and elements can include the use of filtration in the system to help extend membrane lifespan.

Tubing membranes can be made as a unitary element having parallel sealed channels, or they can be separate tubing elements. If together, the tubing elements could be separated by perforations to enable easy separation. 

1. A system for increasing an efficacy of a fertigation system comprising: a closed-loop irrigation tubing array positionable adjacent a root system of a plant, the irrigation tubing having an inlet for receiving fluid for low-flow delivery to the plant root system; and a circulation pump positioned in-line with the tubing array, for circulating the fluid within the tubing array, thereby substantially equalizing a concentration of a substance within the tubing array, without substantially raising a fluid pressure therewithin.
 2. The system recited in claim 1, wherein the circulation pump comprises a peristaltic pump.
 3. The system recited in claim 1, wherein an outlet of the circulation pump feeds into the irrigation tubing array adjacent the tubing inlet.
 4. The system recited in claim 3, wherein the circulation pump outlet meets the irrigation tubing array at an acute angle.
 5. The system recited in claim 1, wherein an inlet of the circulation pump is positioned adjacent an outlet of the irrigation tubing array.
 6. The system recited in claim 5, further comprising a fluid reservoir for holding fluid to be delivered to the plant root system, the reservoir in fluid communication with the tubing inlet, and an outlet of the circulation pump feeds into the reservoir.
 7. The system recited in claim 6, further comprising a network of outbound tubing sections, inlets thereof in fluid communication with the tubing inlet, and a manifold in fluid communication with distal ends of the outbound tubing sections, the manifold in fluid communication with the circulation pump inlet.
 8. A method for increasing an efficacy of a fertigation system comprising: positioning a closed-loop irrigation tubing array adjacent a root system of a plant; providing fluid at low flow to an inlet of the tubing array; and circulating the fluid within the tubing array, thereby substantially equalizing a concentration of a substance within the tubing array, without substantially raising a fluid pressure therewithin.
 9. The method recited in claim 8, wherein the circulating comprises using a peristaltic pump positioned in-line with the tubing array.
 10. The method recited in claim 9, wherein an outlet of the peristaltic pump feeds into the irrigation tubing array adjacent the tubing inlet.
 11. The method recited in claim 10, wherein the peristaltic pump outlet meets the irrigation tubing array at an acute angle.
 12. The method recited in claim 9, wherein an inlet of the peristaltic pump is positioned adjacent an outlet of the irrigation tubing array.
 13. The method recited in claim 12, further comprising holding fluid to be delivered to the plant root system in a fluid reservoir in fluid communication with the tubing inlet, and an outlet of the peristaltic pump feeds into the reservoir.
 14. The method recited in claim 13, further comprising feeding the fluid into a network of outbound tubing sections, inlets thereof in fluid communication with the tubing inlet, and positioning a manifold in fluid communication with distal ends of the outbound tubing sections, the manifold in fluid communication with the peristaltic pump inlet. 